An irradiation effect in Nova DN Gem 1912 and the significance of the period gap for classical novae |
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| Authors: | A Retter E M Leibowitz T Naylor |
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| Institution: | Department of Physics, Keele University, Keele, Staffordshire ST5 5BG; School of Physics and Astronomy and the Wise Observatory, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University,
Tel Aviv 69978, Israel |
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| Abstract: | Continuous CCD photometry of the classical nova DN Gem during 52 nights in the years 1992–1998 reveals a modulation with a period of 0.127844 d. The semi-amplitude is about 0.03 mag. The stability of the variation suggests that it is the orbital period of the binary system. This interpretation makes DN Gem the fourth nova inside the cataclysmic variable (CV) period gap, as defined by Diaz & Bruch, and it bolsters the idea that there is no period gap for classical novae. However, the number of known nova periods is still too small to establish this idea statistically. We eliminate several possible mechanisms for the variation, and propose that the modulation is driven by an irradiation effect. We find that model light curves of an irradiated secondary star fit the data well. The inclination angle of the system is restricted by this model to 10°? i ?65°. We also refine a previous estimate of the distance to the binary system, and find d =1.6±0.6 kpc. |
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| Keywords: | accretion accretion discs radiative transfer stars: individual: DN Gem stars: individual: V1974 Cyg novae cataclysmic variables |
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